Hick’s Law – a matter of choice

Bill Hicks has obtained legendary status in the world of stand up comedy. At least part of this is probably down to the fact that he died young. There are recordings of Hicks, but relatively few. We don’t have much on which to build a picture of who he was, but what we have is good. This ‘Hicks Law’ reveals an important truth – the value of quality over quantity. But there is another Hick’s Law that describes the mechanics and the mathematics of choice. It reveals how order within options help to manufacture better choices for our users?

What I think…

There are some basic facts that can help you when you’re thinking about choice in user experience architecture.

1. There is a ‘cognitive load’ experienced by a user when they’re asked to make a choice. Choosing requires effort.

2. The amount of effort required is connected to the total number of alternatives – but this isn’t the only factor.

2. Users need to understand the alternatives. Understanding the alternatives means that the user can act as a volitional agent. They need information in order to do this – so that the choice is an informed one.

To make a decision a user must understand the alternatives and be able measure them against each other. This measuring of alternatives requires the user to ‘hold them in their consciousness’ during the decision making process. This is one reason why limiting the number of options is good practice. Users are limited in how much information they can hold at any one time. Attention is finite.

But there are tricks we can employ to stack the odds in our favour. We can introduce an ordering principle into the alternatives which allows a user to group (and ignore) some options, making the process easier.

These are all things that I had thought about and written about before, but it turns out that there is maths to prove it.

Hick’s Law

Hick’s law states that for every additional item, the time required to make a choice will increase. But the important thing about the law is that the relationship between additional items and time isn’t a constant increment – it’s not a straight line thing.

Hick’s law has a logarithmic form. The amount of additional effort that each item added to a list requires isn’t a consistent unit – it’s not like each new item in your menu will add half a second thinking time – at least not in all cases.

If a user who is making a choice needs to give equal attention to each alternative then the increase in time (effort) will be linear. But if we’re clever about the way we present options we can bend time, increase efficiency and reduce the effort required each time a user weighs up the options.

When a user navigates a well-designed menu or set of options they’ll often have the help of some underlying order. Alphabetical order or some other form of categorisation allows users to ignore some of the options and jump straight to their main area of concern. Look at the dropdowns or the menu in your current web browser – the menus are grouped to make it easier to find the function you want.

Hick’s law is a cool thing to think about when you’re considering the number of choices you’re presenting to a user. In fact, I’ve consistently used the word choices – but most things in an interface can be considered a choice when we’re thinking about ease of use and optimising finite attention. So it seems like both Hick and Hicks suggest that quality trumps quantity most of the time.